Spring Session

Spring Session 提供了管理用户会话信息的 API 和实现。Spring Session 使得支持集群会话变得非常简单。

总结：

1. Session 管理变得更方便
2. Session 共享变得更简单

Session 共享

Spring Session 支持透明地利用 Redis 来支持 web 应用的 HttpSession 的共享。

添加依赖和配置

• 依赖

  <dependency>
  	<groupId>org.springframework.session</groupId>
  	<artifactId>spring-session-data-redis</artifactId>
  </dependency>

• 配置

  spring.redis.host=localhost
  spring.redis.password=password
  spring.redis.port=6379
  
  spring.session.store-type=redis

启动时，会得到一个错误：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.autoconfigure.session.SessionAutoConfiguration$ServletSessionRepositoryValidator': Invocation of init method failed; nested exception is org.springframework.boot.autoconfigure.session.SessionRepositoryUnavailableException: No session repository could be auto-configured, check your configuration (session store type is 'redis')
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1804) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:953) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.16.jar:5.3.16]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.16.jar:5.3.16]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.4.jar:2.6.4]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:740) ~[spring-boot-2.6.4.jar:2.6.4]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:415) ~[spring-boot-2.6.4.jar:2.6.4]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) ~[spring-boot-2.6.4.jar:2.6.4]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1312) ~[spring-boot-2.6.4.jar:2.6.4]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301) ~[spring-boot-2.6.4.jar:2.6.4]
	at study.helloworld.springsession.SpringSessionSamplesApplication.main(SpringSessionSamplesApplication.java:10) ~[classes/:na]
Caused by: org.springframework.boot.autoconfigure.session.SessionRepositoryUnavailableException: No session repository could be auto-configured, check your configuration (session store type is 'redis')
	at org.springframework.boot.autoconfigure.session.SessionAutoConfiguration$AbstractSessionRepositoryValidator.afterPropertiesSet(SessionAutoConfiguration.java:315) ~[spring-boot-autoconfigure-2.6.4.jar:2.6.4]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863) ~[spring-beans-5.3.16.jar:5.3.16]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.3.16.jar:5.3.16]
	... 16 common frames omitted

是因为缺少下面的依赖：

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

验证

打包后，指定端口启动两个进程：

$ mvn clean package -Dmaven.test.skip=true
$ java -jar -Dserver.port=8080 spring-session-samples-0.0.1-SNAPSHOT.jar
$ java -jar -Dserver.port=8081 spring-session-samples-0.0.1-SNAPSHOT.jar